<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Snake Game</title>
    <style>
        body {
            margin: 0;
            display: flex;
            flex-direction: column;
            justify-content: center;
            align-items: center;
            height: 100vh;
            background-color: #000;
        }

        canvas {
            border: 1px solid #fff;
        }

        .mobile-controls {
            display: flex;
            justify-content: center;
            margin-top: 20px;
        }

        .control-button {
            background-color: #fff;
            border: 1px solid #000;
            padding: 10px 20px;
            margin: 5px;
            font-size: 18px;
            cursor: pointer;
            border-radius: 5px;
        }
    </style>
</head>

<body>

    <canvas id="gameCanvas"></canvas>

    <div class="mobile-controls">
        <button class="control-button" id="left">左</button>
        <button class="control-button" id="up">上</button>
        <button class="control-button" id="down">下</button>
        <button class="control-button" id="right">右</button>
    </div>

    <script>
        const canvas = document.getElementById('gameCanvas');
        const ctx = canvas.getContext('2d');

        const scale = 20;
        const rows = 20;
        const columns = 20;

        canvas.width = columns * scale;
        canvas.height = rows * scale;

        let snake;
        let food;
        let direction = { x: 1, y: 0 };
        let isGameOver = false;
        let baseSnakeColor;
        let foodColor;

        // 随机生成颜色的函数
        function getRandomColor() {
            const r = Math.floor(Math.random() * 256);
            const g = Math.floor(Math.random() * 256);
            const b = Math.floor(Math.random() * 256);
            return `rgb(${r}, ${g}, ${b})`;
        }

        function Snake() {
            this.body = [{ x: 10, y: 10 }];

            this.draw = function () {
                for (let i = 0; i < this.body.length; i++) {
                    const gradientFactor = i / this.body.length;
                    // 通过调整颜色实现渐变效果，头部颜色较深，尾部颜色较浅
                    const r = Math.floor(255 * (1 - gradientFactor)); // 以红色基调为例
                    const g = Math.floor(100 * gradientFactor); // 可根据需要调整
                    const b = Math.floor(150); // 固定一个蓝色调
                    ctx.fillStyle = `rgb(${r},${g},${b})`;

                    ctx.fillRect(this.body[i].x * scale, this.body[i].y * scale, scale, scale);
                }
            };

            this.update = function () {
                const newHead = {
                    x: this.body[0].x + direction.x,
                    y: this.body[0].y + direction.y
                };

                // 检查蛇是否撞墙或与自身碰撞
                if (newHead.x < 0 || newHead.x >= columns || newHead.y < 0 || newHead.y >= rows || this.isCollision(newHead)) {
                    isGameOver = true;
                }

                this.body.unshift(newHead);

                if (newHead.x === food.x && newHead.y === food.y) {
                    generateFood();
                } else {
                    this.body.pop();
                }
            };

            // 检查蛇是否与自身碰撞
            this.isCollision = function (pos) {
                for (let i = 0; i < this.body.length; i++) {
                    if (this.body[i].x === pos.x && this.body[i].y === pos.y) {
                        return true;
                    }
                }
                return false;
            };
        }

        // 生成食物，确保食物不会生成在蛇身体上
        function generateFood() {
            let isOnSnake;
            do {
                isOnSnake = false;
                food = {
                    x: Math.floor(Math.random() * columns),
                    y: Math.floor(Math.random() * rows)
                };

                // 检查食物是否生成在蛇身体上
                for (let i = 0; i < snake.body.length; i++) {
                    if (snake.body[i].x === food.x && snake.body[i].y === food.y) {
                        isOnSnake = true;
                        break;
                    }
                }
            } while (isOnSnake); // 如果食物生成在蛇身体上，重新生成

            foodColor = getRandomColor(); // 每次生成新的食物时，食物颜色变化
        }

        // 绘制食物
        function drawFood() {
            ctx.fillStyle = foodColor;
            ctx.fillRect(food.x * scale, food.y * scale, scale, scale);
        }

        // 游戏主循环
        function gameLoop() {
            if (isGameOver) {
                alert('Game Over');
                window.location.href = 'student.html';
                // document.location.reload();
                return;
            }

            ctx.clearRect(0, 0, canvas.width, canvas.height);
            snake.update();
            snake.draw();
            drawFood();

            setTimeout(gameLoop, 200);  // 控制游戏速度（200ms 间隔）
        }

        // 控制蛇的方向
        window.addEventListener('keydown', (e) => {
            switch (e.key) {
                case 'ArrowUp':
                    if (direction.y === 0) direction = { x: 0, y: -1 };
                    break;
                case 'ArrowDown':
                    if (direction.y === 0) direction = { x: 0, y: 1 };
                    break;
                case 'ArrowLeft':
                    if (direction.x === 0) direction = { x: -1, y: 0 };
                    break;
                case 'ArrowRight':
                    if (direction.x === 0) direction = { x: 1, y: 0 };
                    break;
            }
        });

        // 移动端控制按钮
        document.getElementById('left').addEventListener('click', () => {
            if (direction.x === 0) direction = { x: -1, y: 0 };
        });

        document.getElementById('right').addEventListener('click', () => {
            if (direction.x === 0) direction = { x: 1, y: 0 };
        });

        document.getElementById('up').addEventListener('click', () => {
            if (direction.y === 0) direction = { x: 0, y: -1 };
        });

        document.getElementById('down').addEventListener('click', () => {
            if (direction.y === 0) direction = { x: 0, y: 1 };
        });

        // 初始化游戏
        baseSnakeColor = getRandomColor(); // 在游戏开始时生成蛇的基色，并且保持一致
        snake = new Snake();
        generateFood();
        gameLoop();
    </script>

</body>

</html>
